Ultra-fine, dry powders, also known as micro- and nano-powders, are the subject of increasing interest in pharmaceutical manufacturing, because they provide a solution to many of the shortcomings of blended drugs. Active drug ingredients are produced, packaged and administered to the patient as pure, dry powders, without blending them with solvents or other agents. Elimination of the blending steps simplifies the manufacturing process, reduces development and manufacturing costs, makes dosage more accurate, and extends the drug's shelf life.
The drawback of dry powders is that they are difficult to handle, tending to clump and stick in storage and to scatter when disturbed by even slight air movements. These handling problems must be overcome if dry powder drugs are to be used efficiently and safely, and special methods must be used for accurate dose processing and administration. A number of companies, such as Delsys Pharmaceutical Corp., of Princeton, N.J., have developed pharmaceutical manufacturing processes using electrostatic forces to deposit fine powders onto a substrate. Electrostatic deposition is the same principle as is used in dry-toner copying machines. The technique is used to form and encapsulate dry powders into pills for oral administration.
Other drug delivery modalities have been adapted for use with dry powders. For example, dry powder inhalers have gained acceptance in drug delivery to the lungs. PowderJect Pharmaceuticals plc, of Oxford, England, is developing a powder injection device for intradermal delivery of vaccines and other drugs. The device shoots powder particles into the skin at supersonic speed, taking the place of a syringe.